1. Field of the Invention
The present invention relates to an image processing apparatus, an imaging apparatus, an image processing method, and a computer program. In more detail, the present invention relates to an image processing apparatus, an imaging apparatus, an image processing method, and a computer program which display a list of thumbnail images corresponding to images selected from among multiple pieces of video image data obtained by photographing using a video camera, for example, and perform a process of starting playback of a video with a position corresponding to a specified one of the thumbnail images in the list.
2. Description of the Related Art
Today, many imaging apparatuses, such as digital cameras or digital video cameras, and many image processing apparatuses, such as DVD players, have a function of displaying a list of image data stored in a storage medium on an image display section or a monitor, for example.
For example, some imaging apparatuses or DVD players capable of playing a video have a capability to display a menu in which a title and chapters of the video are arranged, allow a user to select a desired content from the displayed menu, and play the selected content. Further, some devices are capable of performing a so-called index display process. The index display process is a process of displaying, in size-reduced (thumbnail) form, an image representative of a video obtained by one photographing process, that is, from start to end of photographing, using an imaging apparatus, for example. This makes it possible to start playback of the video with a frame of that image displayed on a display in size-reduced form, using this image as an index.
When indices of video data are displayed, size-reduced images of frames that are selected from among all the frames that constitute the video data are displayed. Accordingly, in order to allow the user to easily grasp contents of the video data, as significant frames as possible have to be selected, as index-use images, from among the video data. One technique for achieving this is described in Japanese Patent No. 3312105, for example. According to this technique, a search is performed in video image data using an object dictionary in which an image of an object to be searched for has been registered, so that an image that resembles the registered image will be selected as an index-use frame image. The registration of the image of the object to be searched for in the object dictionary is performed beforehand by learning.
According to this technique, an index image corresponding to the specific registered object can be selected from among one unit of data obtained by one recording operation (this unit of data will be hereinafter referred to as “one content”), and prior registration of the object image is required. This technique has a problem in that images corresponding to unregistered objects may not be selected as indices. Suppose, for example, that a plurality of people appear in different time periods in the same content. In this case, a frame that includes a face of a person corresponding to a specific registered object can be selected as an index, while frames that include only other people may not be displayed as indices. Such a technique has a problem in that a face (e.g., a face of a child of the user's) which the user desires to be displayed as an index image may not be displayed as an index image.
In an application (hereinafter referred to as a “face index”) such as a video camera that displays images of faces included in a video image when displaying indices of the video image, it may not be reasonable to display all faces that are included in the content (i.e., the video image) as the indices. For example, when a scene (e.g., a choral competition, a field day, etc.) in which many faces appear has been photographed, images of too many faces will be displayed as indices. An original purpose of displaying the indices is to enable quick grasp of an outline of the content. When too many faces are displayed as indices as in the above example, this purpose is not accomplished.